CVE-2023-53845

In the Linux kernel, the following vulnerability has been resolved:

nilfs2: fix infinite loop in nilfsmdtget_block()

If the disk image that nilfs2 mounts is corrupted and a virtual block address obtained by block lookup for a metadata file is invalid, nilfsbmaplookupatlevel() may return the same internal return code as -ENOENT, meaning the block does not exist in the metadata file.

This duplication of return codes confuses nilfsmdtget_block(), causing it to read and create a metadata block indefinitely.

In particular, if this happens to the inode metadata file, ifile, semaphore irwsem can be left held, causing task hangs in lockmount.

Fix this issue by making nilfsbmaplookupatlevel() treat virtual block address translation failures with -ENOENT as metadata corruption instead of returning the error code.